In order to improve the power performance of a snowmobile, its drivability and stability must be optimized by improving the running comfortability and grounding characteristics of the steering ski. In order to meet this requirement, there has been proposed in the prior art the so-called strut type steering ski suspension system which is suitable in widening the upward and downward movable range (or cushion stroke) of the steering ski, and which provides excellent turning characteristics. A suspension system of this type is equipped with a stationary cylinder fixed to a frame, a movable cylinder slidably held in the stationary cylinder, and a steering ski attached to the lower end portion of the movable cylinder so that the steering ski is forced into contact with the snow ground through the movable cylinder.
In order to improve the turning characteristics and the running stability, it is sufficient to widen the spacing (or tread) between a right and left steering ski. If, however, the aforementioned strut type suspension system is adopted to enlarge its cushion stroke, its total length in the vertical direction is so enlarged that its upper portion will protrude upward from the chassis, which is conventionally formed into a rounded shape, especially from the engine cowl. Therefore, it is impossible to widen the tread so much. Thus, there has been desired a strut type suspension system which can reduce its vertical length while keeping its cushion stroke as long as possible.
The present invention contemplates to provide a steering ski suspension system for snowmobiles, which is suitable in elongating the cushion stroke while reducing the vertical length. In order to attain this objective a cylindrical shock absorber with a gas chamber is arranged in a movable cylinder such that its cylinder is positioned below, and a rod compensating chamber for compensating the pressure fluctuations in the cylinder of the aforementioned shock absorber due to the entrance and exit of a rod is disposed in the vicinity of the lower end portion of the aforementioned movable cylinder outside of it.
The invention will be fully understood from the following detailed description and the accompanying drawings, in which: